The technology of transverse flux guidance for electrical machines has been known for several decades. However, transverse flux machines are considered to be complicated to produce and known transverse flux machines nowadays actually have a large number of different components in comparison to conventional electrical rotating machines, whose assembly is time-consuming and therefore costly.
On the other hand, conventional electrical machines for drive technology require special adaptations for power transmission, for example on the mechanical side, such as a reduction gearbox, in order to allow an appropriately high torque, for example, to be passed to the rotor hub of a wind power station. This gearbox is not only associated with additional costs but also requires space, accommodation, and friction losses. These adverse features can be avoided only if drives can be designed without a gearbox. A high torque is required for this purpose, which can be provided by a transverse flux machine with its excellent characteristics in terms of specific torque and efficiency. For this reason, a transverse flux machine appears to be particularly suitable for use as a direct drive machine.
Irrespective of their good characteristics, until now, there has not been any major interest in large-scale manufacture of transverse flux machines, because they are complicated to produce.
DE 35 36 538 A1 discloses soft-iron elements with a U-profile which are installed, corresponding to the number of pole pairs, in a stationary machine part, and close the magnetic circuit. In this case, the moving machine part is in the form of an internal rotor in the form of a disk; it has an alternating sequence of permanent magnets on its disk surfaces, which are arranged at right angles to a rotor axis, for excitation purposes. These permanent magnets are subject to centrifugal forces corresponding to the rotation speed of the machine, and this can represent a major load on the adhesive connection between such permanent magnets and the rotors.
DE 195 47 159 A1 discloses a transverse flux machine which acts as an external rotor machine with rotating soft-iron elements. Although its design represents a better design variant than DE 35 36 538 A1 with regard to the centrifugal forces that occur, its design, in contrast, is comparatively complex, since the rotor elements which revolve on the outside are held by means of an annular structure for each phase.
WO 2006 126552 discloses an electrical machine for conversion of electrical energy to mechanical energy and vice versa, comprising a moving part and a stationary part, wherein, in the case of transverse magnetic flux guidance, the moving part is in the form of an inner rotor without windings, wherein the rotor comprises at least two magnetic conductors, which are separated from one another axially, for magnetic flux guidance, such that a first and a second impeller wheel are formed, and the stationary part comprises a number of magnetically acting webs in the circumferential direction of the machine, which are operatively connected to the magnetic conductors of the rotor, wherein this stationary part has at least one first winding structure which is likewise operatively connected to the axially separated magnetic conductors of the rotor.